1. Field of the Invention
The present invention relates to a medium format camera using Brownie film that is provided with an interchangeable film holder. More specifically, the invention relates to a camera having a data imprinting device for imprinting data, such as a date, time, shutter speed, aperture value, etc. on each frame of the film at the time of exposure.
2. Description of the Related Art
Many recently-produced 35 mm cameras, which use 35 mm film, are provided with a data imprinting device for imprinting data (i.e., photographic data) such as a date, time, shutter speed, aperture value, etc. on each frame of the film (film frame) at the time of exposure.
In a 35 mm camera provided with such a data imprinting device, a tiny or small window or opening is generally formed on the pressure plate at a position opposed to either an upper or lower film guide rail formed on an aperture frame having a rectangular photographic aperture. In addition, and a character generator including LEDs is typically disposed behind the aforementioned tiny window.
This character generator emits light to be projected towards the film frame to be exposed in accordance with character information output from a CPU. The emitted light carries a certain image of a pattern of characters and is incident on the back of the film frame via an image forming optical system and the tiny window to thereby imprint the photographic data on the film frame as a latent image.
Although such a data imprinting device is widely used in 35 mm cameras, no medium format camera using Brownie film and having an interchangeable film holder is provided with such a data imprinting device due to the following reasons.
In imprinting an image of the emitted character pattern on the film frame by means of the aforementioned type of data imprinting device, it is important that the planarity of the film at a portion where the photographic data is to be imprinted should be positioned within the depth of focus of the image forming lens of the data imprinting device. Therefore, it is preferable that the photographic data be imprinted on either an upper or lower margin of that part of the film frame which is positioned between the upper and lower guide rails.
However, in a medium format camera using Brownie film that is provided with an interchangeable film holder, it is generally impractical for the photographic data to be imprinted on the film frame to be exposed from either the front or rear thereof. In the case where the photographic data is intended to be imprinted on the film frame to be exposed from the front thereof, i.e., on the photosensitive surface of the film frame, it is necessary for the data imprinting device to be disposed in front of the film frame. However, it is impossible to have such a disposition because a focal plane shutter is generally positioned immediately in front of the film frame. In the other case where the photographic data is intended to be imprinted on the film frame to be exposed from the rear thereof, i.e., from the side of the pressure plate, it is again very impractical to have such an arrangement because the film holder having the pressure plate is interchangeable with respect to the camera body, which makes it impossible to secure space for installation of the data imprinting device at a position opposed to either the upper or lower film guide rail.
The interchangeable film holder is generally provided with two parallel guide rollers, i.e., first and second guide rollers, arranged to be opposed to respective ends of the pressure plate in the film moving direction. The film is first wound around the first guide roller, subsequently wound around the second guide roller and finally wound around the film take-up spool.
Brownie film is a type of film roll consisting of a spool, film and paper with the film and paper being attached together and wound around the spool. Due to such a structure, there is a slight difference between the inner and outer circumferences of the attached paper and film. Therefore, there are tendencies that the film is taut while the paper is slack between the Brownie film roll (i.e., the spool of the Brownie film) and the first guide roller, and that the paper is taut while the film is slack between the second guide roller and the film take-up spool.
Due to such tendencies, it is technically possible for the photographic data to be clearly imprinted on the film at a portion thereof between the Brownie film roll and the first guide roller. However, it is impractical for the photographic data to be imprinted at that portion of the film because the imprinting process will come before the time of exposure for the corresponding film frame. It is also technically possible for the photographic data to be imprinted on the film at another portion thereof between the second guide roller and the take-up spool. In this case, however, it is difficult to imprint the photographic data clearly on the film because the position of the surface of the film at that portion changes between the second guide roller and the take-up spool due to the variation in the amount of slack of the film.
Accordingly, the aforementioned type of medium format camera equipped with a data imprinting device is strongly expected to be produced.
In addition, 35 mm cameras which can take pictures in either regular or panorama sized modes at each shot may be equipped with a data imprinting device for imprinting the photographic data on each frame within its range of exposure (i.e., within the range where subject images are to be exposed) at the time of exposure in either the regular or panorama sized modes. In this type of data imprinting device, the light having a certain image of a pattern of characters which is projected from the character generator of the data imprinting device is usually divided by a fixed prism or the like into two for regular and panorama photographies, respectively, and when the photographic data is to be imprinted on the film for one of the regular or panorama photography modes, one of the two divided lights which corresponds to the currently selected photographic size is allowed to be incident on the film while the other of the two divided lights which corresponds to the currently non-selected photographic size is intercepted so as to not reach the film.
Due to such a structure, in such a conventional type of regular/panorama size selectable type of camera equipped with the data imprinting device, the imprinting position relative to the film frame at which the photographic data is to be imprinted is fixed and thus cannot be changed for each shot. That is, for example, the photography data cannot be imprinted on a film frame within its range of exposure at one shot and also imprinted on another film frame out of its range of exposure at another shot.
In such a conventional type of regular/panorama size selectable type of camera equipped with the data imprinting device, it is also impossible to change the imprinting position depending upon the type of photographic data. That is, for example, it is impossible to imprint the date, time, etc. on the film frame within its range of exposure while imprinting a shutter speed and an aperture value on the same film frame out of its range of exposure.
Furthermore, in such a conventional type of regular/panorama size selectable type of camera equipped with the data imprinting device, since the light projected from the character generator of the data imprinting device is divided into two by the fixed prism or the like as mentioned before, the quantity of each of the two divided lights is small, which makes it impossible to imprint the photographic data on the film frame sharply and clearly.